The objective of the current proposal is to clone and sequence the human Factor IX genes from both normal individuals and individuals suffering from hemophilia B in order to define the molecular mutations in hemophilia B. Cloning will be accomplished by using lambda vectors. Nucleotide sequenced will be determined by the Maxam-Gilbert method and analysed by various computer programs. The restriction endonuclease polymorphisms at the Factor IX gene locus will be analysed. This analysis will provide information on the mutations in hemophilia B. These studies will make the Factor IX genes available. The availability of both normal and defective genes will aid in prenatal and antenatal diagnosis of hemophilia B and also aid in the isolation of genes of related disorders.